One of the world's busiest airports is looking to become one of the world's greenest.
France's main airport, Paris Charles de Gaulle, handles more than 60 million people a year and its owner-operator, Aéroports de Paris, has set ambitious green targets for CDG and its other airports and airfields in the Paris region.
These include a commitment to cut 'internal CO2 emissions' by a quarter compared to 2009 levels, improved management of rainwater, as well as cutting paper consumption by five percent compared to 2010.
The stakes are high: according to Ademe, France's Environment and Energy Management Agency, the electricity consumed at CDG alone is roughly equivalent to a city of 125,000 people.
One key initiative at CDG is the installation of a biomass plant that has two wood-fired boilers, which meets around a quarter of the airport's heating needs "without releasing fossil-fuel CO2 emissions," according to Aéroports de Paris.
Installed in 2012, the boilers burn 80 tons of woodchips every single day. The wood is sourced from forests surrounding the airport.
As well as wood pellets from trees, CDG is also embracing solar energy. A "solar farm" with 792 solar panels was set up in 2013. On average, the farm is able to produce 157 megawatt hours annually, according to Aéroports de Paris.
The green initiatives at the airports reflect a shift in the attitude of the aviation industry when it comes to mitigating the environmental impact of air travel and airports.
In the U.K. Heathrow Airport – Europe's busiest – has also set its own energy targets. These include an ambition to cut CO2 emissions from buildings by 34 percent by 2020 when compared to 1990 levels and a commitment to cut emissions from the airport's vehicles year on year.
Back in Paris, authorities are keen to push forward with their green ventures. "There's a bold side to this," Hubert de Reboul, Head of Heritage at Aéroports de Paris, told CNBC's Sustainable Energy.
"That's probably what I liked when I learnt that the company was starting up a wood boiler project," de Reboul added. "It was surprising, and so it was bold. What the company is hoping for is that by 2020, [of] all of the energy we need, 25 percent will come from so called 'sustainable' technologies."